john, what are the pitfalls that are facing the candidates possibly? >> for governor romney, he's got two jobs: one is to say why the president has failed and the second is to sell himself. to do that job, he has to be aggressive, kind of in the president's face. for the second job he has to offer something people find attractive so the challenge for him is getting the mix right. the challenge for the president is staying on script, talking about how he has been working for the middle-class and not getting knocked off by governor romney who he doesn't have a great deal of personal regard for. so he has to not look defensive. >> pelley: john, thank you very much. we'll be back later tonight with cbs news live coverage of the debate. that's 9:00 eastern time and 6:00 in the west. today secretary of state hillary clinton promised a full and open investigation into the terror attack on the u.s. consulate in benghazi, libya, three weeks ago. four americans, you'll recall, were killed, including ambassador chris stevens. there are a lot of questions about wh